Add sample extension that allows setting plugin-specific content settings.

chrome/common/extensions/docs/examples/extensions/plugin_settings/options/js/deletable_item_list.js

Index: chrome/common/extensions/docs/examples/extensions/plugin_settings/options/js/deletable_item_list.js
diff --git a/chrome/common/extensions/docs/examples/extensions/plugin_settings/options/js/deletable_item_list.js b/chrome/common/extensions/docs/examples/extensions/plugin_settings/options/js/deletable_item_list.js
new file mode 100644
index 0000000000000000000000000000000000000000..4d2e68edc3f1c10fb7c411a4b2caf310ba37baa5
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@@ -0,0 +1,185 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('options', function() {
+  const List = cr.ui.List;
+  const ListItem = cr.ui.ListItem;
+
+  /**
+   * Creates a deletable list item, which has a button that will trigger a call
+   * to deleteItemAtIndex(index) in the list.
+   */
+  var DeletableItem = cr.ui.define('li');
+
+  DeletableItem.prototype = {
+    __proto__: ListItem.prototype,
+
+    /**
+     * The element subclasses should populate with content.
+     * @type {HTMLElement}
+     * @private
+     */
+    contentElement_: null,
+
+    /**
+     * The close button element.
+     * @type {HTMLElement}
+     * @private
+     */
+    closeButtonElement_: null,
+
+    /**
+     * Whether or not this item can be deleted.
+     * @type {boolean}
+     * @private
+     */
+    deletable_: true,
+
+    /** @inheritDoc */
+    decorate: function() {
+      ListItem.prototype.decorate.call(this);
+
+      this.classList.add('deletable-item');
+
+      this.contentElement_ = this.ownerDocument.createElement('div');
+      this.appendChild(this.contentElement_);
+
+      this.closeButtonElement_ = this.ownerDocument.createElement('button');
+      this.closeButtonElement_.classList.add('raw-button');
+      this.closeButtonElement_.classList.add('close-button');
+      this.closeButtonElement_.addEventListener('mousedown',
+                                                this.handleMouseDownUpOnClose_);
+      this.closeButtonElement_.addEventListener('mouseup',
+                                                this.handleMouseDownUpOnClose_);
+      this.closeButtonElement_.addEventListener('focus',
+                                                this.handleFocus_.bind(this));
+      this.appendChild(this.closeButtonElement_);
+    },
+
+    /**
+     * Returns the element subclasses should add content to.
+     * @return {HTMLElement} The element subclasses should popuplate.
+     */
+    get contentElement() {
+      return this.contentElement_;
+    },
+
+    /* Gets/sets the deletable property. An item that is not deletable doesn't
+     * show the delete button (although space is still reserved for it).
+     */
+    get deletable() {
+      return this.deletable_;
+    },
+    set deletable(value) {
+      this.deletable_ = value;
+      this.closeButtonElement_.disabled = !value;
+    },
+
+    /**
+     * Called when a focusable child element receives focus. Selects this item
+     * in the list selection model.
+     * @private
+     */
+    handleFocus_: function() {
+      var list = this.parentNode;
+      var index = list.getIndexOfListItem(this);
+      list.selectionModel.selectedIndex = index;
+      list.selectionModel.anchorIndex = index;
+    },
+
+    /**
+     * Don't let the list have a crack at the event. We don't want clicking the
+     * close button to change the selection of the list.
+     * @param {Event} e The mouse down/up event object.
+     * @private
+     */
+    handleMouseDownUpOnClose_: function(e) {
+      if (!e.target.disabled)
+        e.stopPropagation();
+    },
+  };
+
+  var DeletableItemList = cr.ui.define('list');
+
+  DeletableItemList.prototype = {
+    __proto__: List.prototype,
+
+    /** @inheritDoc */
+    decorate: function() {
+      List.prototype.decorate.call(this);
+      this.addEventListener('click', this.handleClick_);
+      this.addEventListener('keydown', this.handleKeyDown_);
+    },
+
+    /**
+     * Callback for onclick events.
+     * @param {Event} e The click event object.
+     * @private
+     */
+    handleClick_: function(e) {
+      if (this.disabled)
+        return;
+
+      var target = e.target;
+      if (target.classList.contains('close-button')) {
+        var listItem = this.getListItemAncestor(target);
+        var selected = this.selectionModel.selectedIndexes;
+
+        // Check if the list item that contains the close button being clicked
+        // is not in the list of selected items. Only delete this item in that
+        // case.
+        var idx = this.getIndexOfListItem(listItem);
+        if (selected.indexOf(idx) == -1) {
+          this.deleteItemAtIndex(idx);
+        } else {
+          this.deleteSelectedItems_();
+        }
+      }
+    },
+
+    /**
+     * Callback for keydown events.
+     * @param {Event} e The keydown event object.
+     * @private
+     */
+    handleKeyDown_: function(e) {
+      // Map delete (and backspace on Mac) to item deletion (unless focus is
+      // in an input field, where it's intended for text editing).
+      if ((e.keyCode == 46 || (e.keyCode == 8 && cr.isMac)) &&
+          e.target.tagName != 'INPUT') {
+        this.deleteSelectedItems_();
+        // Prevent the browser from going back.
+        e.preventDefault();
+      }
+    },
+
+    /**
+     * Deletes all the currently selected items that are deletable.
+     * @private
+     */
+    deleteSelectedItems_: function() {
+      var selected = this.selectionModel.selectedIndexes;
+      // Reverse through the list of selected indexes to maintain the
+      // correct index values after deletion.
+      for (var j = selected.length - 1; j >= 0; j--) {
+        var index = selected[j];
+        if (this.getListItemByIndex(index).deletable)
+          this.deleteItemAtIndex(index);
+      }
+    },
+
+    /**
+     * Called when an item should be deleted; subclasses are responsible for
+     * implementing.
+     * @param {number} index The index of the item that is being deleted.
+     */
+    deleteItemAtIndex: function(index) {
+    },
+  };
+
+  return {
+    DeletableItemList: DeletableItemList,
+    DeletableItem: DeletableItem,
+  };
+});